Bacterial Genotyping of Central Nervous System Tuberculosis in South Africa: Heterogenic Mycobacterium tuberculosis Infection and Predominance of Lineage 4

Genomic characteristics of prospectively sequenced Mycobacterium tuberculosis from respiratory and non-respiratory sources

Understanding the differences between Mycobacterium tuberculosis strains isolated from respiratory and non-respiratory sources may inform clinical care and control strategies. We examined demographic and genomic characteristics of all culture-confirmed M. tuberculosis cultures isolated from respiratory and non-respiratory sources in New South Wales, Australia, from January 2017 to December 2021, using logistic regression models. M. tuberculosis strains from 1,831 patients were sequenced; 64.7% were from respiratory, 32.1% from non-respiratory, and 2.2% from both sources. Female patients had more frequent isolation from a non-respiratory source (p = 0.03), and older adults (≧65 years) from a respiratory source (p < 0.0001). Lineage 2 strains were relatively over-represented among respiratory isolates (p = 0.01). Among 39 cases with sequenced isolates from both sources, 43.6% had 1-10 single nucleotide polymorphism differences. The finding that older adults were more likely to have M. tuberculosis isolated from respiratory sources has relevance for TB control given the expected rise of TB among older adults.

Central nervous system tuberculosis

PURPOSE OF REVIEW

Central nervous system (CNS) tuberculosis is the most devastating form of tuberculosis (TB), with mortality and or neurological sequelae in over half of individuals. We reviewed original research and systematic reviews published since 1 January 2019 for new developments in CNS TB pathophysiology, diagnosis, management and prognosis.

RECENT FINDINGS

Insight in the pathophysiology is increasing steadily since the landmark studies in 1933, focussing on granuloma type classification, the relevance of the M. tuberculosis bacterial burden and the wide range of immunological responses. Although Xpert/RIF has been recommended by the WHO for extrapulmonary TB diagnosis, culture is still needed to increase the sensitivity of TB meningitis diagnosis. Sequential MRIs can improve understanding of neurological deficits at baseline and during treatment. Pharmacokinetic/pharmacodynamic modelling suggests that higher doses of rifampicin and isoniazid in TB meningitis could improve survival.

SUMMARY

Recent studies in the field of CNS-TB have largely focussed on TB meningitis. The outcome may improve by optimizing treatment dosing. This needs to be confirmed in clinical trials. Due to the important role of inflammation, these trials should be used as the platform to study the inflammatory and metabolomic responses. This could improve understanding of the biology of this disease and improve patient outlook by enabling individualised host-directed therapy.